Intake silencer and air cleaner



June 3, 1941 H. s. KAMRATH 2,243,866

INTAKE SILENCER AND AIR CLEANER Filed Nov. 20, 1935 34 WN 38 A9 20 F i 5/ 55 M 1 53 awe/WM Patented June 3, 1941 INTAKE SILENCEB AND AIR CLEANER Herbert G. Kamrath, Flint, Mich, assignor to General Motors Corporation, Detroit, Mich, a

corporation of Delaware Application November20, 1935, Serial No. 50,745

3 Claims.

This invention has to do with air cleaner and silencer assemblies and relates principally to the silencer elements thereof.

In one of its aspects, the invention relates to resonator silencers in which there are included a number of chambers which encircle the main duct and resides in an arrangement of passages for connecting the chambers to the main duct.

In another aspect, the invention relates to means for eliminating the hissing noise due to sound waves of high frequency which usually accompanies the rapid flow of air through .a duct and resides in means for eliminating this noise without obstructing the flow of the air through the duct.

For a better understanding of the nature and objects of this invention, reierence is made to the following specification wherein there is described the preferred embodiment of the invention which is illustrated in the accompanying side wall it, an upper end wall I l whose outer edge is seated on an outturned flange on the upper end of the wall it and a lower end wall I! whose outer edge is spun over an outtumed flange on the lower end of the wall III. In the end wall ii, there is formed a central opening axial with and or larger diameter than the tube II but is 01' smaller diameter than the portion 01' the tube I! with which it is telescoped and, consequently, defines with the tubes it and i3 annular passages 38 and 31 which interconnect the chambers ii and It with the duct Ill-ll and with the chambers constitute simple bottle type resonators.

which is encircled by an outwardly extending tube II which is inte ral with the wall. In the end wall ii, there is formed a central opening in which there is secured an inwardly projecting tube ll whose inner end is telescoped within the inner end of the tube II. The tube It is coaxial with and is made of smaller diameter than the tube I: so that the overlapping Portions of the tubes will be spaced apart radially.

The compartment defined by the duct It-il and the walls II, II and I! is divided into upper and lower chambers i5 and it by an annular partition ll whose outer edge is secured in the Joint between the outer edge of the wall I! and the lower end of the wall II. In the opening in the wall ll, there is secured a tube It which encircles the lower end of the tube It and extends upwardly into the chamber l5 and downwardly through the chamber it into the tube II to the same level as the tube ll. The tube III is co- The resonator silencer element which has been described is capped by an inverted. generally cupshaped hood it. In the side wall of the hood, there are a number of generally rectangular openings Ill and in the top of the hood there are three large sectoral openings 2| which are separated by the legs 22 of a spider which is integral with the hood. The hood is secured to the resonator silencer element and the upper and side walls of the resonator silencer element are secured together by spinning a flange on the lower edge of the side wall of the hood around the flange on the upper end of the wall iii of the resonator silencer element. The openings 2| in the top of the hood are closed by a cover. 23 which is lined with a pad 24 of sound absorbing material, such as telt. The cover 23 is detachably secured to the spider at the Junction of its legs 22 by a stud 2! and a wing nut 28.

In the joint between the hood I! and the resonator silencer element, there is secured the outer edge of a generally hat-shaped element 21 which, because of its shape and the fact that the wall Ii is stepped downwardly just within the wall III, is spaced well above the upper wall of the resonator silencer element except at its outer edge.

In the upper wall of the element 21, there is formed an opening II which is coaxial with and of about the same diameter as the tube I4 and bounded by an inwardly and downwardly curved flange. To the inner wall of the element 21, about midway between its top and bottom, there is secured the outer edge 01' an annular element 30 whose central opening Ii is coaxial with and of about the same diameter as the opening 28 and bounded by a similar inwardly and downwardly curved flange. The element 3|! subdivides thereoess defined by the element 21 and the wall Ii into recesses 28 and 32 which communicate with the axial passage in the hood and resonator silencer element through the apertures 30 and it between the inner edges of the elements 21 and II and the wall ll. These apertures, together.,with the recesses into which they lead are known as and will be'hereinafter referred to as "hiss gaps.

The crown of the element 21 is encircled by a filter element which consists oi inner and outer cylindrical screens 38 and M whose interspace is filled with a suitable filter medium 3|. The lower end or the filter element is seated in an annular channel in the rim oi the element 21 and the top oithehoodbearsagainsttheupperendoithe filter element and holds it in place. It will be noted that the inner wall the filter element is spaced from the upright wall of the element II by reason of the fact that the latter is ofiset inwardly just after it departs from the rim.

The air cleaner and silencer assembly which is shown in the drawing was designed for installation on an internal combustion engine with the tube It connected to the air intake orifice of the carburetor so that it cleans the air which enters the carburetor and silences the so-called "intake" noises oi the engine. Although the assembly has beendescribedasiiitweretobeinstalledin th upright position in which it is shown in the drawing, it may, 01' course, be installed "upside down or with the duct l8--ll extending horizontally or at any inclination.

when the assembly is installed in the described manner and the engine on which it is installed is operating, the suction oi the engine draws air from the atmosphere through the openings II into the hood II and thenw, through the filter element "-44-", over the element 21 and through the openings 2. and Si and the duct ll-il into the carburetor and cylinders of the engine.

The filter element frees the air 0! foreign matter and the sound absorbing material 24, the hiss gaps "-2! and 8H! and the resonators Il -Ii and "-4. eliminate the so-called intake noise 0! the engine.

While, oi course, the presence of the several elements of the assembly which are located on the atmospheric side of the resonators increases the silencing efiiciency oi the resonators by decreasing the acoustical conductivity of the portion oi the passagei'rom the engine to the atmosphere which is ated on the atmospheric side oi the resonate essentially. each oi the silencing elements has its own iob to do. The sound absorbing material II, of course, eliminates components of the intake noises which are due to sound waves of high frequency.

The components of the intake nomes due to sound waves of high frequency which are not sufiiciently attenuated by the sound absorbing material are eliminated by the hiss gaps "-2! and 3H! whose silencing characteristics depend upon the volumes of the recesses II and I2 and the dimensions oi the apertures a and I0. It will be noted that the hiss gaps Il-2l and 39-32 are difi'erentiy tuned, i. e., differ in recess volume and aperture dimensions, so that each of them removes a dliierent component of the intake noises. It will, of course, be understood that the number of his gaps which should be employed on any given silencing job, and their recess volumes and aperture dimensions, depends upon the characteristics of the noises which are to be eliminated thereby and, consequently, that, while in the assembly which is shown in the drawing there are incorporated two hiss gaps of particular recess volumes and aperture dimensions, a greater or lesser number of his gaps with difi'erent recess volumes and aperture dimensions may be found necessary or suiilcient in similar assemblies designed for use on other engines.

The components of the intake noises which are due to sound waves of relatively low irequencies are eliminated by the resonators 36-" and Il-ii oi which each is tuned in the manner set iorth in the Wilson application, Serial No. 470,700, filed July 25, 1930, and the corresponding foreign patents, viz., Canadian Patent No. 348,037, British Patent No. 391,180, French Patent No. 720,811 and Italian Patent No. 300,087, so that it responds to and attenuates by resonance certain oi the sound waves from which these components of the intake noises result.

I claim:

1. In an appliance oi the class disclosed. a member shaped generally like a brimmed hat and imperiorate except for an orifice of smaller diameter than its crown in the top 0! its crown. a member in which there is an orifice joined to the outer and spaced from the inner edge 0! the brim oi the first-specified member with the orifice in it alined with the orifice in the firstspecified member to define a. duct through which gases and sound waves may travel, and an annular partition which is disposed between the secend-specified member and the top of the crown oi th first-specified member with the orifice in it alined with the orifices in the first and secondspecified members and subdivides the recess bounded thereby lengthwise into sound wave attenuating recesses which open radially into the duct.

2. In a silencer, a duct through which gases and sound waves may travel, walls which define with the duct a compartment which encircles and communicates with the duct as a side branch, and a member shaped generally like a brimmed hat and imperiorate except for an orifice oi smaller diameter than its crown in the top 0! its crown which is mounted on the compartment and disposed over one end thereoi with its brim nearest the compartment, its orifice alined with the duct and its inner edge spaced lengthwise of the silencer from the nearest end wall of th compartment so that it defines therewith a continuation oi the duct and a relatively deep and narrow sound wave attenuating which opens into it radially throughout its circumferonce.

3. In a silencer, a duet which includes two partly telescoped, radially spaced tubular members through which gases and sound waves may travel, walls which with the duct define a com,- partment which encircles and communicates with the duct as a side branch through the aperture between the tubular members, a member shaped generally like a brimmed hat and imperforate except for an orifice of smaller diameter than its crown in the top of its crown which is mounted on the compartment and disposed over one end thereof with its brim nearest the compartment. the orifice in it alined with the duct and its inner edge spaced lengthwiseot the silencer from the nearest end wall of the compartment so that it defines therewith a continuation or the duct and a recess which opens into it radially, and an annular partition which is disposed between the top of th crown of the member which is shaped generally like a brimmed hat and the mentioned end wall oi the compartment with the orifice in it aiined with the orifice in the top 0! the crown of the member which is shaped generally like a brimmed hat and subdivides the mentioned recess lengthwise into narrower sound wave attenuating recesses which open radially into the mentioned continuation of the duct.

HERBERT G. KAIMR-ATH.

CERTIFICATE OF CORRECTION. Patent No. 2,2h5 866. n 5, 9L

I HERBERT G. KAMRATH.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 2, second column, line 1414., claim 2, after "attemzating" insert the word --recess--;' and that the said Letters Patent should be resdwith this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 22nd day of July, A. D. 19in.

Henry Van Arsdale, (Seal) Acting Commissioner ofPatents. 

